QD-Final Exam

Instrumental analysis in QD

•Stereomicroscope

•Electrostatic Detection Apparatus (ESDA)

•Micrometer

•Ribbon Analysis Workstation (RAW)

•Transmitted Light Box

•UV Light Box

•Video Spectral Comparator (VSC)

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\*mostly non-destructive analyses (evidence isn’t altered, preserved in original state)

Instrumental analysis in QD (chemical)

•Scanning Electron Microscopy (SEM)

•Gas Chromotography-Mass Spectroscopy (GC-MS)

•Fourier Transform Infrared Spectroscopy (FT-IR)

•Thin Layer Chromotography

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\*utilized less; sometimes involves destructive testing; ink analysis also

Stereomicroscope

* Used to microscopically examine documents

→Handwriting

→ Printing processes

→ Indented impressions w/ side lighting

* Typically magnifies 1x-60x
* Usually first instrument used when examining a document

Why is the microscope always necessary, regardless of examination type?

allows the FDE to see what the unaided eye cannot: stroke direction, pen pressure, intricacies of printing, and indented writing

Electrostatic Detection Apparatus (ESDA)

•Originally developed to detect fingerprints on documents (1978)

•Eventually marketed as a technique to develop indented writing

•Also successful in preserving indented writing for future analyses

Micrometer

•Used to measure paper thickness

•Micron: 1 x 10-6

•Multiple measurements should be taken around the paper to get an accurate measurement

→ usually necessary when insertions of different papers into a contract or other body of documents is suspected (different properties than others)

Ribbon Analysis Workstation (RAW)

* When typing, carbon from ribbon gets deposited on document; creates a void in the carbon ribbon
* RAW digitally captures voids on ribbon and creates transcript of what was typed
* Mechanically moves the ribbon in front of a camera, which “reads” the voided areas on the ribbon
* Alternatively, the examiner can manually twist/rewind the ribbon and write/type what is on the ribbon…what a pain!

Transmitted Light Box

* Transmitted light, or lighting from below, is utilized to look for a variety of things on a document

→ Watermarks

→ Insertions

→ Holes (staple or otherwise)

→ Patches

→ Alterations

* Assist in determining whether a document is genuine or counterfeit, visualizing writing beneath white out, or finding holes/inconsistencies in a document that are unable to be visualized with normal lighting

UV Light Box

* An ultraviolet (UV) light box typically has 254nm and 365nm of light

→ 254nm: short wave (dangerous to eyes)

→ 365nm: long wave

* Place documents within the box and turn on UV light to visualize features of documents
* Gives a lot of insight on genuine/altered/counterfeit before full examination


* Useful in visualizing:

→ UV security printing on documents

→ Differences in inks

→ Areas that have been washed

→ UV bright or dead paper

Video Spectral Comparator (VSC-8000)

* workhorse of the lab
* more features that allow for greater on screen examination and comparison of exhibits; recording function and various overlay functions
* also has smaller and portable systems
* 90K so usually only 1 or 2 per lab

4 main components of the VSC

1. Desktop computer
2. Digital video camera
3. Photographic filters
4. Variable light sources

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* allow for the recording and visualization of the substrate under a wide range of lighting conditions and through a variety of filters
* reaction of the substrate to the variety of conditions allows for determinations in a variety of casework

VSC spectrum

•Short Wave UV (200nm to 300nm)

•Long Wave UV (300nm to 400nm)

•Visible Portion (400nm to 700nm) (human eye is sensitive to)

•Near IR (700nm to 1100nm)

The VSC8000 provides excitation light from __*___*__ nm to ___nm

254 nm to 1100 nm

4 actions of light

1. Reflection
2. Absorption
3. Transmittance
4. Luminescence

Reflection

* All wavelengths of visible light may reflect off an object, making it appear white

→ normal ambient visible light (coming from the sun) has all the colors in it

Absorption

All wavelengths of visible light may be absorbed by an object, making it appear black

How do we see color?

When a range of wavelengths in the visible portion of the spectrum strike an object, certain wavelengths can be absorbed while others are reflected (eyes perceive whatever is reflected back as color)

Transmittance

* Sometimes an object, such as glass, absorbs certain wavelengths and transmits others
* Wavelengths of light that are hitting an object pass through the object
* Object may transmit at one wavelength and absorb at another ; ink that appears black in visible portion of the spectrum may transmit light in the infrared portion of the spectrum

Luminescence/Fluorescence

* Shorter wavelengths of light can be absorbed at a shorter wavelength (after excitation) and then re-emitted as longer wavelengths, an action which may cause an ink to luminesce

→ longer wavelength= lower energy, shorter= higher energy

Zoom range of the VSC

* Can magnify up to 60x


* Can also switch to external camera attached to microscope

VSC-Graphing ink spectrums

* Spectrum analysis feature
* User is able to determine if inks that may appear similar to the unaided eye actually have different spectral graphs
* Subtle difference in response to a given set of lights and filters can be further analyzed and perhaps differentiated in this way

VSC in examination

•Alterations

•Obliterations

•Faded Documents

•Document Authentication

•Torn/Cut Edge Comparisons

•Paper Comparison

•Ink Comparison

•Indented Writing

\-can do inter-comparison of multiple documents

\-comparing with video and still images (powerful tool for casework)

VSC-Altered documents

rest of the writing on the check is absorbing the IR light applied (black entries), while the “00” is luminescing (appears bright)

→ due to inks that are compositionally different

→ can’t tell if it was fraudulently done or a different person but can only say if it was two different inks

Reflection vs. Luminescence

reflection will be seen as flat white and a little more dim

What type of light behavior is useful in obliteration cases?

transmittance (unique based on the combo of inks used)

→ hopefully, obliteration ink will transmit light under IR while the original ink will absorb, allowing it to be read

VSC-Low-contrast mediums

* Items with very low contrast can be visualized based on their differing reactions to light (trick is finding right combo of lights and filters; VSC8000 makes it easier)

→ Function that can automate examination of a document

→ Examiner can choose varying conditions, place the document in the VSC, press start and walk away; VSC will then run the various conditions and take pictures

→ Analyst can return, view the photos, and complete the examination but looking more closely at the document under a few conditions rather than consume large amounts of time looking at numerous conditions

UV security features

* Lots of official documents have features you can only see under UV light


* Comparison of a genuine to a counterfeit would make it obvious that they are different; but need to have genuine because counterfeit does have some UV features (just not the same)

Anti Stokes security feature

* Green dot; somewhat common on security documents and credentials

→ Different light source that, when applied to an anti-stokes reactive ink, creates a colored reaction in the visible spectrum for the examiner to observe

→ Green= shorter wavelength, higher energy

Retro (or coaxial) reflection security feature

* Another light source on the VSC
* Typically used in brand protection
* When light strikes an object along the same axis as light enters the camera, it changes the appearance of certain security features

Secret writing

* AKA invisible ink/concealments; a lot of cases from the prison system
* Some are indentations (easily visualized with side lighting); others rely on body fluids (saliva, semen, urine; juices)
* When you don’t know what you are dealing with, you don’t want to add a variety of chemicals to try and visualize the note as you may end up destroying the evidence all together (VSC can screen and examine without destroying)

Urine has ____ properties under UV light

fluorescent; dip utensils into it to write

Fluorescent documents

* Sheets of paper appear the same in white light
* UV light may indicate a sheet was inserted in the middle of a contract (or at least that a different paper type was used)
* Quick screen for possible differences in brighteners or other UV sensitive markers

Shredded paper reconstruction

* Manual reconstruction based on color differences, printing, optical properties under UV light, handwriting, printing, etc.
* In theory, a paper’s reactions to light could be used to help sort shredded paper before reconstruction

Torn edges

Using transmitted light, it is easy to visualize and document a fracture match

Cut edge comparisons

* When a document has been cut, security threads that are UV reactive can help to establish that these two parts were once one piece

→ Green and red fluorescent fibers that were literally cut in half during this alteration can be once again aligned

Why must indented impressions be done BEFORE fingerprint examination?

once fingerprint exams are conducted with various solvents and powders, this exam cannot be done and the evidence is lost

How can indented impressions be detected?

* Side/oblique lighting (1st exam)

→ looking at documents for printing processes, surface texture, and handwriting characteristics

→ when doing initial side lighting exam, look at the back as well!

→ shadows are created around areas that are recessed and areas that are raised

* ESDA

Difference between ESDA2 and ESDA?

* ESDA refers to the 1st generation
* ESDA2 is the second generation which has a larger platen and built in timer for the corona

ESDA lite

* For scene processing and is more portable
* Other companies make a machine similar to the ESDA; referred to as an EDD (Electrostatic Detection Device)

Components of ESDA

* __Mylar__- saran wrap like material that is pulled over the document for protection and preservation of observed indentations
* __Platen__- porous bed the document is placed on; allows the vacuum on the system to suck the document flat onto the surface
* __Corona__- contains a tungsten wire that charges to 8kV; imparts charge on document (ions collect in “potholes”)
* __Humidification Chamber__- depending on the humidity of the environment around the paper, the fibers in the paper may be only slightly raised or very raised from the surface (“increase” depth of indented impression)

→ optimal humidity= 60%

\*top of the mylar take on a positive charge which attracts the negatively charged toner on the glass beads (+ charge)

3 toner applications with ESDA

1. Cascade (most commonly used)
2. Aerosol (2nd most common)
3. TAD (which stands for the Toner Application Device, and is rarely used because it takes a lot of finesse and is easy to “erase” your results and have to start over

Types of indented impressions

Sourced

→ source doc with writing present

Unsourced

→ no source doc with writing present

What is done with documents before they are analyzed with the ESDA?

\-humidification for 3-5 minutes (humidification chamber)

\-TAD vs. cascade vs. aerosol methods (mostly cascade, aerosol for light impressions)

\-Adobe Photoshop can be used to enhance impressions (using levels adjustment and Burn Tool with pixel size and hardness parameters)

Original writing will appear ___ while indented impressions appear ____

white; dark

When does ESDA not work?

* deep impressions (plastic), thin/thick papers (tissue/card stock)

→ side lighting used; images can be preserved with VSC

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* stone papers, after fingerprint processing (ninhydrin)

Types of cases in which indented impression examinations are the most helpful

sequence, threatening letters, fraud, and association cases

Can a handwriting examination could be done on an ESDA?

yup, depending on the quality of the ESDA

Types of relief printing

letterpress, typewriting, flexography; raised off the plate

Letterpress

•Plate has raised character surface

•Oldest of the printing processes

•Uses hard metal type

•Uses stiff, viscous ink; high pressure

•“Squeegee” of ink around edges of letters

•Sharp, clear image

•Embossing

•May be imperfect inking

•Can be easily changed so usually final step in creating doc

Flexography

•plate has raised character surface

•plate is rubberized plastic, very flexible

•very fluid ink

•light pressure (can be used for more fragile substrates)

•plates comes into direct contact with substrate (differs from offset)

•ink ring around edges of image/letters

•little or no embossing

•uneven inking, small voided areas

•possible air bubbles

•used for packaging material

Intaglio

2nd oldest printing process; recessed into surface; think ink and high pressure; very expensive; gravure= thin ink and lighter pressure

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Characteristics:

•Raised image

•Crisp image/fine detail

•Some feathering of ink along edges

•Varying thickness of ink

•Reversed embossing evidenced on the back of paper

Intaglio: Rotogravure/Gravure

•Visible cell pattern (circular dots, donut style pattern with voids)

•“Saw-toothed” edge

•No embossing

•No raised image

•Thin, low viscosity ink

•not good at producing microprint

Screen printing

•character in open area in mesh

→ ink will only go through to areas where mesh screen is open

•porous screen can be made of fine silk, nylon, or stainless steel; no printing plate

•stencils are hand-cut or photo-mechanically produced

•used to be known as “silk screen”

•uses a very thick ink with “mud-paint-like” consistency

•possible bubbles/void pockets

•somewhat raised appearance

•serrated edges

Type of printing often seen with counterfeit credit cards

screen printing

Thermography

•first printed with inkjet, toner or offset, then clear coat of “bubbly” ink

•creates special raised effect in printing, lacks detail of intaglio

•mainly used for small quantity jobs when aesthetic appeal is desired- “Poor Man’s Intaglio”

•uses a slow-drying ink; gives tactile effect like intaglio

So Ho printing machines

•Small Office-Home Office

•represents a large percentage of document production

•legitimate and Illegitimate document production

Planographic printing

character on same plane as plate and plate does not come into direct contact with substrate (uses an intermediate blanket cylinder); ink is held to location by chemical reaction; blanket and impression cylinders are pressing pages together

→ ex. offset lithography

Characteristics of offset lithography

•Smooth, crisp edges to a color

•Flat appearance

•Even inking/uniform coverage

•“Hickeys” may be present

•Can be confused with inkjet because of the dots

Offset with half-tone printing

series of dots in a grid pattern; centers are equidistant (often confused with inkjet)

Standard color units for offset printing

CMYK; cyan (blue), magenta (red), yellow, and black

→ can incorporate pantone colors especially in security docs

Xerography

character on same plane as plate; ink attraction controlled by electromagnetic charge

→ photocopier

→ toner printing

Toner technology

non-impact imaging process employing a photoconductive drum and imaging system



•Five basic steps

–Charging

–Imaging – Laser/Light

–Toner application

–Transfer from drum to substrate

–Fuse toner to paper with heat &/ pressured

–Cleaning

T/F: Copiers are more apt to have defects

true; due to design and use (trashmarks); has unique constellation of extraneous marks not originating from the original image

Sources of individual characteristics from copiers

1. Glass platen (scratched or pitted, soiled-FP, correction fluid, adhesives)
2. Blanket or inside of lid cover (spoiled or damaged, only seen when doc is smaller than output paper)
3. Imaging lens (dust or debris)
4. Paper feed grippers and rollers (indentations-visualized with ESDA or side lighting)
5. Imaging drum (scratched or pitted; defects will move because drum moves

Where will imaging drum defects move along?

along the axis of the paper feed

Do imaging drum defects appear on each copy?

may not; large drum have three images on the at a time

→ defect would only appear every third copy

Why may defects on appear on successive pages?

size of drum, positioning of original on platen

\-defects will stay in relative position to each other, may be transient

(machine can be cleaned or serviced), may “disappear” with change in mode (adjustment of density), may be from original document not from machine itself, apparent defects may not repeat

Common Source Determination – no device

Comparing two questioned documents to determine if they are from a common source

→ similar methodology as previous without taking exemplars from the machine

→ analyze and compare class characteristics

→ analyze and compare individual characteristics

→ evaluate observations and consider variable or limitations

Examination procedure for copiers

•Analyze documents for possible defects

•Make overlay of questioned document (drawn or photocopied)

•Compare overlay to questioned document (verify which trashmarks are from original)

•Use overlay on other documents (compare trashmarks from questioned to known documents or other questioned documents)

Inkjet

dots are NOT in a pattern

→ absorbs into paper fibers (toner sits on surface)

→ commonly available on printers, some copiers

→ liquid dots of CYM and/or K

→ no embossing

→ satellites aka overspray

Inkjet technology

•Non impact imaging system employing a print head with nozzles that spray ink droplets

•Drop on demand or continuous (method of getting ink drops onto paper)

Impact dot matrix technology

impact method of imaging that employs a series of pins that presses into a fabric ribbon transferring dot matrix image onto the substrate

→ commonly found on printers (old printers, industrial printers, receipt printers)

→ series of inked ribbon impression dots (woven pattern in dots)

→ embossed dots

→ stepped edges

→ paper often has perforated edges (due to feeding mechanism of printers)

How is the US Postal Money order printed?

impact dot matrix (if you don’t see it, it’s probably counterfeit)

Thermal mass technology

Thermal mass transfer (TMT)- thermal imaging system that employs an array of heated elements to transfer pigmented wax from a transfer ribbon onto a substrate; creates readable film ribbon

Characteristics of TMT

•commonly available on printers, labelers, facsimiles (common method of producing receipts)

•no embossing

•stepped edges

•layer of wax-like substance fused to paper

•sits on surface

Dye Diffusion Thermal Transfer (D2T2)

thermal imaging system with colored dyes that diffuse into the substrate based on varying amounts of heat applied to the heating elements; creates a photographic quality continuous tone image

Characteristics of D2T2

•commonly available on printers (common with ID card printers)

•no embossing

•grid-like pattern

•unfocused or fuzzy quality

•sits on surface

Which is more precise: screen printing or thermal mass?

thermal mass

Examination of printed documents

1. Classification of printing process

→ what type of device produced doc; any investigation lead info
2. Source determination

→ did doc originate from particular device
3. Common source association

→ did these 2+ docs originate from same source
4. Determining the generation of a copy

→ how many times doc has been copied

Source determination

1. Compare doc to an office machine device to determine origin
2. Obtain known from office machine (collected: doc produced during similar time period of questioned doc, requested: recreate situation of questioned doc; use same/similar variables-ink, toner, ribbon, paper, mode)
3. Take request exemplars from machines with a platen (lid down-no paper-default/darkest/lightest density and lid up-plain white paper-default/darkest/lightest density)
4. Analyze and compare Q and K for class characteristics (type of tech, toner components)
5. Analyze and compare for individual characteristics (wear and damage, misalignments, reproducible marks, void areas, improper/extraneous toner transfer)
6. Evaluation of SD (ID through elimination: “*It was determined that the submitted K1 prepared the Q1 letter*.”)

Evaluation of source determination-ID

combination of class characteristics and several repeating individual characteristics

Evaluation of source determination-Qualified opinion

combination of class and individual characteristics with limitations

Evaluation of source determination-Elimination

class characteristics that are different with no explanation

–differences in individual characteristics does not mean an elimination

–differences in class characteristics does not mean an elimination if explainable

What variables can affect an output doc?

mode of printing, substrate, interchangeable parts

Sumerians

1st to record historical events on clay tablets (clay allowed for records to be portable)

Cuneiform

Sumerian system of writing (dates back 3000 years)

Egyptians

first to use traditional “pen and paper” system (reeds with sharpened chewed ends and papyrus)

Middle East

qalams (different ones for differing degrees of fineness); valued objects

Romans

scribes wrote on papyrus or wax with a stylus (metal rod)

Quill pens

displaced reed; most used writing instrument during Middle Ages

→ made from wings of goose (left side better)

→ square cut (Gothic), pointed nib (round hand), shading, non-consistent due to manual application of ink

Fountain pens

•Modern nib style pen with reservoir of ink in cartridge

•Popular before the introduction of the ballpoint pen

•Ink reservoir attached and ink flows through nibs to page



Characteristics:

\-varying line thickness depending on change in writer’s hand pressure, change in angle of pen to paper, rotation changes in nib’s axis

\-shading of characters

\-embossing on back of paper

\-scratches from defective pen from nib wear

\-consistent intensity of ink throughout the writing

Ballpoint pens

•Most successful pen of modern times (ease of ink flow)

•Small rotating ball that fits in a socket-like device

•Tube with ink is attached to the ball

•Ball rotates and ink flows thru the ball and transfers to substrate

•Ink contains dyes and is non-aqueous

•Characteristics: shiny under magnification, “troughs” in ink line, can determine pen pressure easily

Rollerball pens

•Ball mechanism through which ink flows from cartridge

•More aqueous ink than ballpoint ink

•Thin ink sinks into the sheet much more than ballpoint

•Feathering of ink line

Gel pens

•Ball mechanism through which ink flows from cartridge

•Water-based ink with pigments

•Highly viscous ink; thicker than rollerball

•Sinks into sheet and feathers like rollerball

•Appears feathered under magnification (not as much as rollerball)

Erasable ballpoint pens

•Much thicker than regular ballpoint ink

•Can use eraser on end to erase up to 1 month after writing

•Gooping, skipping, grooves in writing surface, “stringing” (fine ink cobweb near line)

Porous tip marker

•Marker with plastic casing and inner ink reservoir (sharpie, highlighter)

•Ink flows out of porous tip (through tiny holes in the tip to create a larger, more spread-out appearance of the ink)

•Very fluid, aqueous ink

•Saturates page with much thicker line

•Lots of ink feathering

Pencil

•wooden casing with graphite (to write)/clay encased inside (more clay=harder pencil lead)

•small pieces of graphite present under magnification

•indentation along the line of writing

•absorbs at high wavelengths

•Liquid lead pencil: graphite within liquid carrier, characteristics similar to bp pen; failed to gain acceptance

Pencil can be seen with an IR filter up to ___ nm

1000

Metal ring of a pencil that holds the eraser on

ferrule

Ink chemistry

Non-destructive: microscopic, VSC

Destructive: TLC, GC/MS